KR920006976B1 - Temperature control means - Google Patents

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Description

Temperature control means

1 is a side view of a thermostat used for measuring viscosity provided with a temperature control means according to the invention.

2 is a system diagram of a temperature control means according to the present invention.

3a is a flow chart of a preferred software program routine for the temperature control means according to the invention.

FIG. 3b is a flow chart of a preferred subroutine for use in the routine of FIG. 3a.

4 is a graph of experimental results of liquid storage and fluid sample temperature control according to the present invention.

5 and 6 are graphs of another two experimental results of liquid reservoir and fluid sample temperature control according to the present invention.

7 shows an experimental study of the heating and cooling of the liquid reservoir under fixed conditions and under the condition that the temperature detection of the fluid sample is directly fed back to the second controller in the temperature control means without using the first controller in the temperature control means. Graph of results.

* Explanation of symbols for main parts of the drawings

1: thermostat 2: viscosity detector

3: fluid sample 6: temperature control device

7: recorder 8: liquid reservoir

11: first thermometer 12: transmitter

13: first controller 17: second controller

18: heating and cooling means

The present invention relates to a temperature control means for a thermostat, and more particularly to a temperature control means for effectively controlling the temperature of the reservoir and the fluid sample over a wide temperature range by measuring the viscosity of the fluid sample submerged in the reservoir of the thermostat. .

In measuring the viscosity of a fluid sample, the temperature of the fluid sample is generally controlled using a thermostat, and water, oil, and the like are used as the liquid for heating and cooling the fluid sample. And the temperature of the fluid sample is indirectly controlled through the temperature control of the liquid. Therefore, it takes a lot of time to adjust the fluid sample temperature to the required specified temperature, and furthermore, when the viscosity of the fluid sample is continuously measured over a wide temperature range, the fixed fluid sample temperature changes over time after the change. It becomes difficult to measure the actual temperature of the fluid sample.

For example, in the capillary viscometer on page 41 of the book "Viscosity" issued by Michiko Kawata, a 1983 revision of Corona Publishing Co., Ltd., the viscometer is submerged in a liquid reservoir of a thermostat and Is taken as the temperature of the fluid sample in the viscometer. However, it takes a long time to determine the relationship between the viscosity and the temperature of the fluid sample due to the fact that the temperature of the fluid sample is not measured directly and the thermal conductivity of the fluid sample depends on the type of sample.

Also, as described on pages 109 to 110 of the book, in a rotary viscometer, the sample container is wrapped in a water jacket and provided with a water reservoir of a thermostat installed outside the jacket to control the temperature of the fluid sample. Water is forcedly circulated between the jackets. In this case, temperature control is performed on the water in the thermostat without the need to feed back the temperature of the sample to the thermostat temperature control, but it is not easy to adjust the temperature of the fluid sample to the required specified temperature. This will be.

Accordingly, the object of the present invention is to eliminate the drawbacks shown in the prior art, and the present inventors have developed an excellent tuning fork vibration-type vibrometer, which is Japanese Patent Laid-Open No. 102736/1984 and US Patent No. 4,729,237, in particular the temperature of a fluid sample is controlled quickly and precisely, the viscosity of the fluid sample being measured using such a good viscometer. Thus, the inventor has accomplished the present invention.

In the present invention, the viscosity of the fluid sample is measured, the temperature of the fluid sample is detected and the detected temperature of the fluid sample is fed back to the temperature control means of the thermostat, the temperature of the thermostat being PID (proportional + integrated + differential). It provides a temperature control means to be controlled. According to the present invention, the temperature of the fluid sample can be quickly and effectively adjusted to any desired temperature required over a wide temperature range.

According to one aspect of the invention, there is provided a temperature control means for temperature control of a fluid sample in a liquid reservoir, the temperature control means comprising: (a) one means for measuring the temperature of the fluid sample in the liquid reservoir; (b) second means for determining a difference between the required sample temperature and the measured sample temperature; (c) if the absolute value of the differential measured by the second means is greater than the expected value, follow the first function of the differential measured by the second means and the absolute value of the differential measured by the second means is greater than the expected value. Third means for determining the required reservoir temperature along the second, differential function measured by said second means if not large; (d) fourth means for determining a difference between the required reservoir temperature and the required sample temperature; (e) if the difference determined by the fourth means is greater than the given value, add the given value to the required sample temperature; and if the difference determined by the fourth means is less than the negative value of the given value, the given value is subtracted from the required sample temperature. Fifth means for limiting the required reservoir temperature determined by the third means to build; (f) sixth means for measuring the reservoir temperature; (g) seventh means for determining the difference between the required reservoir temperature from the third and fifth means and the measured reservoir temperature, and (h) by the seventh means, to have the effect of zeroing the difference. Means for heating or cooling the liquid reservoir as a function of the determined differential.

The temperature control means further comprises means for periodically repeating the functions of the above described means (a)-(h), and according to another feature of the invention, there is provided a method for controlling the temperature of a liquid reservoir The method includes the steps of (a) measuring the temperature of a fluid sample in a liquid reservoir; (b) determining the difference between the required sample temperature and the measured sample temperature; (c) when the absolute value of the differential determined in step (b) is less than the expected value, determining the required reservoir temperature along the second function of the differential determined in step (b); (d) determining the difference between the required reservoir temperature and the required sample temperature; (e) add the given value to the required sample temperature if the difference determined in step (d) is greater than the dimension given above, and give the given sample temperature at the required sample temperature if the difference determined in step (d) is less than the negative of the given dimension; Limiting the required reservoir temperature determined in step (c) to subtract; (f) measuring the reservoir temperature; (g) determining the difference between the required reservoir temperature from step (e) and the measured reservoir temperature, and (h) liquid reservoir as a function of the differential determined in step (g) to have an effect of zeroing the differential. Heating or cooling.

In a preferred embodiment, the temperature control means has a dependent control system, which system responds to the detected temperature of the fluid sample (which changes over time) to adjust the appropriate specified temperature of the thermostat (which changes over time). And first and second controllers operated in accordance with a computer program that calculates at the appropriate time. This allows the fluid sample to be detected so that the fluid sample temperature is quickly adjusted to the required specified temperature without causing any over shoot or under shoot of the liquid reservoir temperature to the specified temperature of the fluid sample. It is effectively heated or cooled by the operation of the temperature controller according to the present invention.

The designated temperature of the thermostat is determined according to one of the first and second operating equations described as a function of the difference between the specified temperature of the fluid sample and the measured temperature. Moreover, the heating and cooling of the thermostat are effectively controlled in accordance with the PID action formed in the second controller.

In FIG. 1, the viscosity of the fluid sample 3 is measured by being contained in the sample container 4 and submerged in the liquid reservoir 8 of the thermostat 1. The viscosity sensor of the viscous detector 2 and the temperature probe of the first thermometer are immersed in the fluid sample, where the viscous detector 2 and the first thermometer 11 are fixed by the stand 5 and the fluid sample 3 Temperature and viscosity are detected by the detector 2 and the thermometer 11. Each of these temperatures and viscosities is represented in the recorder 7. This record 7 produces an output signal corresponding to the detected temperature of the fluid sample 3 and inputs the signal to the temperature controller 6 of the thermostat 1.

In FIG. 2, the first thermometer 11 detects the temperature of the fluid sample 3, and the transmitter 12 attached to the first thermometer measures an output signal corresponding to the detected temperature of the fluid sample 3. (Hereinafter referred to as a first output signal) is made and the first output signal is input to the first controller 13. In the first thermometer, a resistance thermometer, a dummyistor or a thermocouple thermometer composed of a pretinium resistance wire is preferably used.

The required temperature of the fluid sample 3 is input in advance to the first controller 13 by the input means 14, and the first controller 13 detects the required temperature of the fluid sample and the detected temperature of the fluid sample. The designated temperature of the liquid reservoir 8 is calculated according to one of the first and second manipulations expressed as a function of the difference between the values (changes over time).

The first and second operating formulas will be described below, and the first controller 13 can control any one of the controlled first and second signals corresponding to the respective designated temperatures of the reservoir calculated by each of the two operating circuits. And input the controlled signal to the second controller 17. The second thermometer 15 detects the temperature of the liquid reservoir 8 and the transmitter 16 attached thereto has an output signal corresponding to the detected temperature of the liquid reservoir 8 (hereinafter referred to as the second output signal or less). And input the second output signal to the second controller 17.

The second controller 17 forms an operating signal corresponding to the level of difference between the second output signal and the controlled signal input to the controller. And a PID controlled signal formed based on the operating signal for PID control of heating and cooling means 18 operation.

This heating and cooling means 18 heats or cools the liquid reservoir 8 according to the PID controlled signal. In many experiments, the above-mentioned first, second, and absolute values of the difference between the specified temperature of the fluid sample and the detected temperature are above 2 ° C. above the expected temperature, and when the absolute value is equal to or smaller than the expected value. It was found that the two operations are preferably performed. Moreover, it is preferable to use the following general expressions (1) and (2) as the first and second operations.

T _bs = T _S + k _P x (T _S -MS (i))... … … … … … … … … … … … … … (One)

And,

Where T _bs is the nominal temperature of the liquid reservoir and T _s is the required nominal temperature of the fluid sample. τ represents a control period formed by a time interval between repeated inverse speeds determining the specified temperatures of the liquid reservoir, and M _s (i) and M _s (j) represent the i th and Each of the detected temperatures of the fluid sample in the j-th iteration state, K _p is the ratio of the ratio, and Kl is the integral constant. The values of K _p and K _l are determined from the results of temperature control experiments in advance of using such as thermostats, reservoir medium, fluid sample containers, and the like.

As can be seen from the foregoing, the designated temperature of the liquid reservoir changes in accordance with the detected temperature change of the fluid sample.

In the present invention, the functions of the first and second controllers are preferably performed by one programmed microprocessor, whereby the functions of the controllers are provided. A flowchart of the routine for performing this function is shown in FIGS. 3A and 3B. The program is designed to repeat the routine at a given same time interval, and in Figure 3a, each of the routines begins at step 50 and ends at step 60. In the following, to briefly describe each step of the routine, the words "value of temperature", "specified temperature", "temperature error" and the like are used to mean each of the electric signal levels commonly used in the steps. The temperature value T _bm of the liquid reservoir 8 measured at the stem 51 is provided from the second thermometer 15, and in step 52 the liquid reservoir temperature error E _{b (m)} is obtained during the first iteration of the routine. As will be described below, the T _bm value provided in step 51 is determined by _로부터 from the designated temperature T _bs of the liquid reservoirs determined in steps 80 and 83. In the stem 53, the liquid reservoir temperature error E _{b (n} ) determined at step 52 and the final liquid reservoir temperature error E _{b (n-1} ) calculated at step 54 of the (n-1) th iteration of the routine. _by) using the power P is calculated using a PID algorithm (algorithm).

The power P thus obtained is then transmitted to the heating and cooling means 18 and the operation of the means 18 is controlled according to this power P. In step 54 the new value of E _{b (n-1)} is specified equal to the E _{b (n)} value for use in the next (n + 1) th iteration. In step 55, the number n of the iteration process is increased by adding 1, and in step 56, the control time defined as the time taken from 0 to n iterations is measured in the timer, and step 57 ), Examine whether the control time is, for example, a predetermined control period tau equal to or shorter than 10 seconds, and if the control time is less than tau, the program is shown in step 58x and in FIG. It jumps over the subroutine 59 of the flowchart and reaches step 60 which is an exit.

If the program repeats the repetition process between step 50 and step 57 until the control time reaches, for example, 10 seconds, in other words, when the control time is equal to τ, the routine is step 58; In step 58, the measured time of the control time is removed from the timer after the control time reaches the control period τ. In other words, the timer is set to zero to newly measure the control time in the subsequent process in the routine repetition. Subroutine 59 then enters step 70 as shown in FIG. 3B.

The subroutine is performed over all time periods in which the timer in step 56 measures the control period τ, for example 10 seconds, and in step 71 the measured temperature value M _{s (i)} of the fluid sample 3 is Provided from the first thermometer 11, at step 72 the fluid sample temperature error E _{s (i)} at the i-th control period measured at step 56 is at step 71 at the specified temperature T _s of the sample. The dimension N _{s (i)} provided is determined by 뺌 and the specified temperature T _s of the sample is determined by the operation of the control system. Determined in step 73 is the integrated value I _{s (i)} of the sample temperature error E _{s (j)} until j increases from 0 to i, where j represents the repeated number of control periods. In step 74, the absolute value E _{s (i)} of the sample temperature error calculated in step 72 evaluates whether the temperature is greater than or less than the expected temperature, for example 2 ° C, and the absolute value E _{s (i)} is 2 ° C. When exceeded, the subroutine is directed to step 75; otherwise, when the absolute value is less than or equal to 2 ° C., the subroutine is directed to step 78.

In step 75, when the absolute value E _{s (i)} exceeds 2 ° C, the integrated value I _{s (i)} obtained in step 73 is removed. The storage tank designated temperature T _bs at step 77 is determined by adding the designated temperature T _s to the proportional value determined at step 76 when E _{s (i)} is greater than 2 ° C. The temperature difference between T _bs and T _{s is} then determined in step 81 and compared with the temperature given in step 82, for example 5 ° C. Alternatively, when it is determined that the absolute value | E _{s (i)} | is not greater than 2 ° C in step 74, the integrated value τ x K _I x I _{s (i)} is determined in step 78. Here, K _I has already been determined, and according to step 78 the proportional value K _p × E _{s (i)} is also determined at step 79. In step 80, the storage tank designation temperature T _bs in the i-th control period is determined by adding the specified temperature T _s of the sample to the numerical values determined in steps 78 and 79.

In step (81), the temperature difference ΔT is determined by subtracting the sample specified temperature T _s from the reservoir designated temperature T _bs . Examine whether the absolute value | ΔT | of the temperature difference at step 82 is an expected temperature value, for example, greater than or not greater than 5 ° C., and when the absolute value is greater than 5 ° C., the subroutine is led to step 82. Alternatively, when it is less than or equal to 5 ° C., the subroutine is immediately passed through step 83 to step 84. Step 83. In step 81, the absolute value is large to │ΔT│ new value of the judgment nanhu T _bs than 5 ℃ within is a (T +5 _s) substantial computation result of T _bs in step 79, or It is specified equal to (T _s -5).

In other words, when the absolute value | ΔT | is determined at step 82 at 5 ° C. or lower, the reservoir designated temperature T _bs remains at the value determined at step 80, and this optional operation is carried out at the temperature of the thermostat 1. In control, an undesirable overshoot or undershoot of the liquid reservoir temperature Tbm relative to the specified temperature Ts of the sample in transition is excluded.

In step 84 the counter for measuring the number of repetitions n of the routine is set to zero, then the subroutine is on step 85 and the putin is on step 60. The sample temperature error determined at step 72 as described above and shown in FIG. 3b is, for example, + 2 ° C. or more or −2 ° C. or less, and the program skips steps 78-80 and instead Steps 75-77 and 81 are performed. This optional procedure is provided for effectively controlling the heating and cooling means 18 via a second controller to heat or cool the liquid reservoir 8 so that the fluid sample temperature can be approached relatively quickly at the sampled temperature. Will be.

Next, the result of the temperature control experiment conducted using the temperature control means according to the present invention will be described with reference to FIGS. 4 to 6, and in FIGS. 4 to 6, A designates a fluid sample. Where temperature represents the detected temperature of the fluid sample, C represents the designated temperature of the liquid reservoir computed by the first controller, and D represents the detected temperature of the liquid reservoir. These temperatures A to D are tracked by a computer and the temperature B of the fluid sample, which is a relatively high viscosity oil liquid, as shown in FIG. 4, is regulated at a specified temperature of 30 ° C. after about 35 minutes and then kept constant. do.

5 and 6 show experimental results obtained using a fluid sample having low viscosity and high thermal conductivity compared to the fluid sample used to achieve the experimental results shown in FIG. As shown in FIG. 3B, the designated temperature C of the liquid reservoir is adjusted to 5 ° C higher or lower in correspondence with the specified temperature of the fluid sample according to the temperature control program as shown in FIG. 7 shows experimental results when the operation of the heating and cooling means 18 is controlled according to a PID controlled signal which is formed on the basis of the difference between the detected temperature of the fluid sample in the second controller 17 and the detected temperature. Shows.

In this experiment, the first controller 13 is not used and a signal corresponding to the designated and detected temperature of the fluid sample is immediately input to the second controller 17, where the detected temperature of the liquid reservoir is There is no feedback to the second controller 17. As shown in FIG. 7, the temperature D of the liquid reservoir pulsates over time, and the temperature B of the fluid sample also fluctuates with a significant response delay and thus does not approach the specified temperature even after a long time.

Claims (14)

A temperature control means for temperature control of a fluid sample in a liquid reservoir, said temperature control means comprising: (a) one means for measuring the temperature of a fluid sample in a liquid reservoir; (b) second means for determining a difference between the required sample temperature and the measured sample temperature; (c) if the absolute value of the differential measured by the second means is greater than the expected value, follow the first function of the differential measured by the second means and the absolute value of the differential measured by the second means is greater than the expected value. Third means for determining the required reservoir temperature along the second, differential function measured by said second means if not large; (d) fourth means for determining a difference between the required reservoir temperature and the required sample temperature; (e) when the difference determined by the fourth means is greater than the given value, add the given value to the required sample temperature and the required reservoir temperature determined by the third means such that the given value is subtracted from the sample temperature required by the fourth means. Is fifth means for limiting; (f) sixth means for measuring the reservoir temperature; (g) seventh means for determining the difference between the required reservoir temperature from the third and fifth means and the measured reservoir temperature, and (h) by the seventh means, to have the effect of zeroing the difference. Means for heating or cooling the liquid reservoir as a function of the determined differential. 2. The temperature control means of claim 1, further comprising means for periodically repeating the functions of means (a)-(h). The method of claim 2 wherein the first function _{T bs = T s + K p} × (T s -M s (i)) having the formula and called herein _bs T = temperature, the required liquid reservoir T _s = fluid The required temperature of the sample, M _s (i) = the measured temperature of the fluid sample in the iteration, and K _p = proportional constant. The method of claim 2, wherein the second function

Where the control period M _s (i is defined as T _bs = required temperature of the liquid reservoir, T _s = required temperature of the fluid sample, and τ = T _bs the time interval between successive iterations of the crystal. And M _s (j) are the measured temperature K _p = proportional constant and K _I = integration constant of the fluid sample in the i-th and j-th iterations of the control period τ. The temperature control means according to claim 1, wherein the estimated temperature for the third means is 2 ° C. The temperature control means according to claim 1, wherein the given temperature for the fifth means is 5 ° C. 5. The temperature control means according to claim 4, wherein the control period is 10 seconds. A method of temperature control of a fluid sample in a liquid reservoir, the method comprising: (a) measuring the temperature of a fluid sample in the liquid reservoir; (b) determining the difference between the required sample temperature and the measured sample temperature; (c) follow the first function of the differential determined in step (b) when the absolute value of the differential determined in step (b) is greater than the expected value and when the absolute value of the differential determined in step (b) is less than the expected value, determining the required reservoir temperature according to the differential second function determined in (b); (d) determining the difference between the required reservoir temperature and the required sample temperature; (e) add the given value to the required sample temperature if the difference determined in step (d) is greater than the dimension given above, and give the given sample temperature at the required sample temperature if the difference determined in step (d) is less than the negative of the given dimension; Limiting the required reservoir temperature determined in step (c) to subtract; (f) measuring the reservoir temperature; (g) determining the difference between the required reservoir temperature from step (e) and the measured reservoir temperature, and (h) liquid reservoir as a function of the differential determined in step (g) to have an effect of zeroing the differential. Heating or cooling the temperature control method. The method of claim 8, wherein steps (a) through (h) are repeated. The method of claim 9, wherein the first function is defined as T _bs = T _s + K _p × (T _s -M _s (i)) where T _bs = the required temperature of the liquid reservoir, T _s = the fluid sample. Temperature required, T _s (i) = measured temperature of the fluid sample in the i-th iteration, K _p = proportional constant. The method of claim 9, wherein the temperature of the liquid reservoir is

Determined by performing the second function, where T _bs = required temperature of the liquid reservoir, T _s = required temperature of the fluid sample, and τ = T _bs defined as the time interval between successive iterations of the determination. The measured temperature, M _s (i) and M _s (j) = the measured temperature of the fluid sampled in the i-th and j-th iterations of the control period τ K _p = proportional constant and K _I = integral constant Temperature control method. 9. The temperature control method according to claim 8, wherein the value expected in step (c) is 2 ° C. 9. A method according to claim 8, wherein the dimension given in step (e) is 5 ° C. 12. The method of claim 11, wherein the control period is 10 seconds.

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